The present invention relates to three-wheel, human powered vehicles, and more particularly to a recumbent vehicle having a main frame formed from a single, bowed tubular member, and an adjustable crank assembly.
A recumbent, human powered vehicle differs from more conventional bicycles in that the recumbent vehicle is constructed so that the cyclist sits behind the pedals in a seat, usually provided with a back rest, in more of a horizontal position than the vertical position normally used in conventional bicycles. Recumbents have been described in the literature as well as various patents. Examples of such vehicles are shown in U.S. Pat. Nos. 3,960,392; 3,981,516; 4,198,072; 4,279,429; 4,283,070; 4,333,664; and 4,373,740.
The advantages of recumbent vehicles over conventional bicycles are well known. The recumbent vehicles are usually safer than the more conventional bicycles because of the feet-forward position of the rider, enabling the rider to brace himself or herself with his or her feet and even stay seated in a head-on collision. The lower center of gravity and feet-forward riding position mean that a high degree of deceleration can be achieved without the rider being pitched forward. Further, the low center of gravity of the rider will significantly reduce front and rear wheel skids which are more often experienced in conventional bicycles.
The unique seating position of the rider in a recumbent vehicle allows for greater power to be applied to the pedals than would ordinarily be possible on a normal bicycle. Further, the horizontal position of the rider provides much improved comfort over conventional bicycles.
Generally, in most recumbent designs, the position of the seat is relatively fixed with respect to the pedal positions, requiring various sized frames for different sized riders. This, of course, affects the bicycle manufacturing costs as well as the inventory requirements of a bicycle supplier and retailer. Further, in past recumbent vehicle designs, the vehicle frames have been very complex, requiring a large number of structural members. The complexity of such frames results in increased manufacturing costs, and in many cases reduced operating efficiency of the vehicle. Further, such past designs are generally awkward, heavy, and not able to be conveniently carried through standard doorways for storage.
In order to overcome the disadvantages of vehicle designs wherein the vehicle seat is relatively fixed with respect to the pedal positions, several designers in the past have proposed structures, in both recumbent vehicles and conventional bicycles, where either the seat or the frame itself is adjustable. U.S. Pat. No. 4,272,095, for example, shows a child's wheeled riding toy having an adjustable front crank and wheel assembly to accommodate different size children. U.S. Pat. No. 3,960,392 discloses a wheeled vehicle for children which has an open centered frame that is dimensionally adjustable longitudinally to accommodate children of different sizes. U.S. Pat. No. 4,152,005 discloses a tricycle for handicapped inviduals which is adjustable to an optimum position for almost any user. None of these patents, however, pertains to a vehicle having a simple frame structure enabling the rapid adjustment of a chain driven crank assembly, in conjunction with a mechanism for adjusting drive chain slack, in order to accommodate different sized riders.
It would be advantageous to provide a recumbent vehicle which is relatively inexpensive to manufacture, is lightweight, and is adapted to accommodate a large range of different sized riders. It would also be advantageous to provide a recumbent vehicle frame which utilizes a minimum of structural members, yet is strong and efficient. Any such recumbent vehicle frame and recumbent vehicle utilizing such frame should provide a comfortable seating arrangement for a rider, which also optimizes the pedaling, and therefore riding, efficiency.
The present invention relates to such a recumbent vehicle and vehicle frame.